18/3.] DISTRIBUTION OF ASIATIC BIRDS. 657 



The Himalaya mountains were divided by Hodgson (see 

 J. A. S. B. 1835) into three zones of elevation, each of which has a 

 more or less distinct fauna; and as these three faunas are characteristic 

 of three different zoological provinces, they are no doubt very natural 

 ones. 



The lowest, from the level of the plains up to about 3000 or 4000 

 feet, including the Terai, is a region of dense jungle, marshy plains 

 at the foot of the hills, steep forest-clad spurs and deep valleys, 

 which preserve the tropical character of their fauna and flora for a 

 long distance into the interior. It is rich in all the most character- 

 istic Indo-Malayan genera, such as Hornbills, Barbets, Kingfishers, 

 Fruit-Pigeons, Bulbuls, and Woodpeckers, the latter in particular 

 being so numerous that, out of eighteen species found in Sikim, all 

 but three occur in the lowest zone. A few representatives of other 

 genera which are more numerously represented in the Malay sub- 

 region also occur, as Hierax eutolmus, Harpactes hodgsoni, Psari- 

 somus dalhousice, Pitta cucullata, Hydrornis nipalensis, and Pohj- 

 plectron chinquis (not found west of the Tista). Along the edge 

 of the forest, and where cultivation has encroached on its limits, some 

 of the commoner birds of the plains are found, whilst on the rivers 

 and marshes many wading birds and waterfowl spend the winter. 

 These, however, rarely enter the hills, though they must pass over 

 them at the period of their migrations. Many Warblers which breed 

 in the upper and middle zones descend during the cold weather to 

 the lower hills and plains, wandering over a great part of India, and 

 in some cases, perhaps, breeding in the higher mountains of the 

 peninsula. Several species of Ruticillince, Motacillince, and Cucu- 

 lidas also descend to this zone in winter ; but if we exclude the 

 wading and water birds, it has not so many species as the zone above it, 

 the numbers being, as well as I can estimate them, about 130 to 260. 



In this zone the fauna is very much the same in character as 

 that of the Malabar coast, Burmah, and Assam, and, though possess- 

 ing many peculiar species of birds, has hardly any genera which are 

 not also found in those countries. 



The transition from the lower zone to the middle is both gradual 

 and irregular, depending much on the peculiarities of different valleys 

 and localities. For instance, at an elevation of 3000-4000 feet in the 

 valley of the little Rungeet, and in that part of the Tista valley which 

 is at a distance from the plains, many of the tropical forms are re- 

 placed by birds of the middle zone ; but it is on the whole undoubt- 

 edly true that the birds of the middle zone from 3000-4000 to 

 10000-11000 feet have a decidedly different character. Here the 

 forest becomes dark and gloomy; oaks, magnolias, and rhododendrons 

 densely covered with mosses and fern replace the saul trees, plan- 

 tains, and giant bamboos of the lower region. In many places the 

 mountains from about 7000 to 9000-10,000 feet are covered by a forest 

 of hill bamboo, so dense that it is impossible to go off the beaten 

 path without clearing a way with the knife. 



Among these small bamboos, and in the rhododendron-woods 

 which are such a characteristic feature of the middle zone, are found 



Proc. Zool. Soc— 1873, No. XLII. 42 



